Communication apparatus, control method, and storage medium

ABSTRACT

A communication apparatus includes a transition unit and a control unit. In a case where a wireless communication path to each of a first base station and a second base station is established, the transition unit transitions from an RRC_CONNECTED state to an RRC_INACTIVE state compliant with a 3rd Generation Partnership Project (3GPP) standard. In a case where the transition unit transitions to the RRC_INACTIVE state, the control unit performs control to selectively execute operating in a first mode for waiting for a notification signal from each of the first and second base stations or operating in a second mode for waiting for a notification signal from either the first base station or the second base station, based on a state of the communication apparatus.

BACKGROUND Field

The present disclosure relates to a communication apparatus that canconnect to a plurality of networks.

Description of the Related Art

A communication apparatus (user equipment (UE)) connected to a fourthgeneration (4G) public wireless communication line transitions between aplurality of states. More specifically, the communication apparatustransitions between two states, i.e., RRC_CONNECTED, which is a statewhere a communication band is secured and unicast data communication isbeing performed, and RRC_IDLE, which is a state where the communicationband is not secured and the unicast data communication is not performed.In the RRC_IDLE state, the communication apparatus can only receivebroadcast data.

In a communication apparatus connected to a fifth generation (5G) NewRadio (NR) public wireless network, RRC_INACTIVE is added to the abovetwo states. In the RRC_INACTIVE state, a communication band is securedand unicast data communication is not performed. In other words, thecommunication apparatus can only receive broadcast data. Using thetransition between a plurality of Radio Resource Control (RRC) states,it is possible to save power and make efficient use of wirelesscommunication resources.

US2013/0163497 discusses a mobile station that identifies whether aplurality of carrier bands in a carrier aggregation is continuous orintermittent, and can switch a timer for intermittent reception that isinstalled for a primary cell and a secondary cell to be common orindependent. Intermittent reception control corresponding to thetransmission cycle of a control signal from a base station is executedin the carrier aggregation, whereby it is possible to save the highpower consumption of the mobile station.

SUMMARY

In fifth generation (5G) New Radio (NR), a communication apparatus canuse dual connectivity (DC), in which the communication apparatusconnects to a plurality of base stations (BSs) via a public wirelesscommunication line and simultaneously provides communication services. Aplurality of carriers is bundled between the plurality of base stations,whereby it is possible to perform broadband data communication.

However, the 3rd Generation Partnership Project (3GPP) standard does notdefine details of operation of the communication apparatus that is usingtwo base stations based on DC in a case where the communicationapparatus transitions to RRC_INACTIVE.

More specifically, the 3GPP standard defines that, during RRC_INACTIVE,the communication apparatus needs to monitor a paging channel (PCH),which is a control channel via which a control signal transmitted from abase station in use to all communication apparatuses in a cell isreceived. However, the 3GPP standard does not define whether thecommunication apparatus that is executing DC needs to monitor a PCH fora base station for a master cell group or a PCH for a base station for asecondary cell group during RRC_INACTIVE.

During RRC_INACTIVE, if the communication apparatus continues monitoringthe PCHs for both the base station for the master cell group and thebase station for the secondary cell group, the standby power increases.

On the other hand, during RRC_INACTIVE, if the communication apparatusmonitors, for example, only the PCH for the base station for the mastercell group, the communication apparatus cannot detect a change inquality of wireless line of the base station for the secondary cellgroup. Thus, the communication apparatus cannot determine whether thecommunication apparatus can return to RRC_CONNECTED based on DC usingthe two base stations until the communication apparatus returns toRRC_CONNECTED. This reduces responsiveness of the communicationapparatus when resuming a service on standby for execution.

According to an aspect of the present disclosure, a communicationapparatus includes a transition unit configured to, in a case where awireless communication path to each of a first base station and a secondbase station is established, transition from an RRC_CONNECTED state toan RRC_INACTIVE state compliant with a 3rd Generation PartnershipProject standard, and a control unit configured to, in a case where thetransition unit transitions to the RRC_INACTIVE state, perform controlto selectively execute operating in a first mode for waiting for anotification signal from each of the first and second base stations oroperating in a second mode for waiting for a notification signal fromeither the first base station or the second base station, based on astate of the communication apparatus.

Further features of the present disclosure will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an example of a hardware andfunctional configuration of a communication apparatus according to afirst exemplary embodiment.

FIG. 2 is a diagram illustrating state transition of the communicationapparatus (user equipment (UE)) defined by the 3rd GenerationPartnership Project (3GPP).

FIGS. 3A, 3B, and 3C are diagrams each illustrating a monitoring stateof paging channels (PCHs) in RRC_CONNECTED and RRC_INACTIVE while dualconnectivity (DC) is being executed.

FIG. 4 is a diagram illustrating an example of a network configurationof a system where a captured image captured by a capture device (UE)that moves between cells is uploaded according to the first exemplaryembodiment.

FIG. 5 is a flowchart illustrating an example of a processing procedureof a monitoring control process executed when the communicationapparatus according to the first exemplary embodiment monitors a movingspeed of the communication apparatus.

FIG. 6 is a flowchart illustrating an example of a processing procedureof a process in which the communication apparatus according to the firstexemplary embodiment checks a PCH signal received from a PCH duringRRC_INACTIVE.

FIG. 7 is a flowchart illustrating an example of a processing procedureof a process in which the communication apparatus according to the firstexemplary embodiment checks the PCH signal received from the PCH whenthe communication apparatus transitions to RRC_CONNECTED.

FIG. 8 is a diagram illustrating an example of a processing sequencebetween the communication apparatus according to the first exemplaryembodiment and a plurality of cell groups when the communicationapparatus moves between a plurality of wireless cells.

FIG. 9 is a diagram illustrating an example of a processing sequencebetween the communication apparatus according to the first exemplaryembodiment and the plurality of cell groups when the communicationapparatus moves between the plurality of wireless cells.

FIG. 10 is a diagram illustrating an example of a processing sequencebetween the communication apparatus according to the first exemplaryembodiment and the plurality of cell groups when the communicationapparatus moves between the plurality of wireless cells.

FIG. 11 is a diagram illustrating an example of a processing sequencebetween the communication apparatus according to the first exemplaryembodiment and the plurality of cell groups when the communicationapparatus moves between the plurality of wireless cells.

FIG. 12 is a diagram illustrating examples of types of uploaded imagesin the system where the captured image captured by the capture device(UE) according to the first exemplary embodiment is uploaded.

FIG. 13 is a block diagram illustrating an example of a hardware andfunctional configuration of a communication apparatus according to asecond exemplary embodiment.

FIG. 14 is a flowchart illustrating an example of a processing procedureof a monitoring control process executed when the communicationapparatus according to the second exemplary embodiment monitors aservice on standby.

DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments for carrying out the present disclosure will bedescribed in detail below with reference to the attached drawings. Theexemplary embodiments described below are examples of implementationmeans of the present disclosure and can be appropriately modified orchanged depending on the configuration of an apparatus to which thepresent disclosure is applied and various conditions. Thus, the presentdisclosure is not limited to the following particular exemplaryembodiments. Further, not all combinations of the features described inthe exemplary embodiments are necessarily indispensable to the solvingmeans of the present disclosure.

A description is given below of an example where a communicationapparatus is capable of performing public wireless communication basedon dual connectivity (hereinafter referred to as DC) compliant with theThird Generation Partnership Project (3GPP) standard. However, thepresent exemplary embodiment is not limited to this example. Forexample, the communication apparatus may use another method capable ofconnecting to a plurality of base stations (BSs) and simultaneouslyproviding communication services.

Further, a description is given below of an example where thecommunication apparatus is an imaging apparatus that can record, in theimaging apparatus, a moving image being captured and can also stream amoving image and distribute a still image via a public wirelesscommunication line, where necessary. However, the present exemplaryembodiment is not limited to this example. The communication apparatusmay be any communication apparatus having a function of executing publicwireless communication based on DC. Examples of the communicationapparatus include a digital video camera, a mobile phone, a smartphone,a personal computer (PC), a laptop computer, and a server, but are notlimited to these examples. The communication apparatus may be a movableobject or a stationary object, or may be included in a movable object.

<Hardware and Function Configuration of Communication Apparatus>

FIG. 1 is a diagram illustrating an example of the hardware and functionconfiguration of a communication apparatus according to a firstexemplary embodiment.

A communication apparatus (user equipment (hereinafter referred to asUE) 1 in FIG. 1 includes a central processing unit (CPU) 101, a randomaccess memory (RAM) 102, a read-only memory (ROM) 103, a fifthgeneration (5G) communication unit 104, a fourth generation (4G)communication unit 105, a global positioning system (GPS) reception unit106, a display unit 107, an operation unit 108, and an image capturingunit 109.

The UE 1 further includes a non-volatile storage unit 110, a movementdetection unit 111, a channel selection unit 112, a power supply sourcedetermination unit 113, and a power unit 114.

The components of the UE 1 in FIG. 1 are connected with each other via asystem bus so that the components can communicate with each other. TheUE 1 does not need to include all of the above modules, and can includeanother module in addition to the configuration in FIG. 1.

The CPU 101 performs overall control on operation of the UE 1 andcontrols the components (102 to 114) via the system bus. Morespecifically, in executing various processes, the CPU 101 implementsvarious functional operations by loading a necessary program from astorage medium such as the ROM 103 or the non-volatile storage unit 110into the RAM 102 and executing the program.

The RAM 102 functions as a main memory and a work area for the CPU 101and temporarily stores a program and data.

The ROM 103 is a non-volatile memory that stores a control program and aparameter that do not need to be changed and that are necessary for theCPU 101 to execute various processes. The control program and theparameter can be stored in the non-volatile storage unit 110, anexternal memory, or an attachable and detachable storage medium (notillustrated).

The 5G communication unit 104 is a communication module for the UE 1 toconnect to a 5G public wireless communication network.

The 4G communication unit 105 is a communication module for the UE 1 toconnect to a 4G public wireless communication network.

The GPS reception unit 106 receives a signal from the GPS.

The display unit 107 displays and outputs, for example, an imagecaptured by the image capturing unit 109 and stored in the non-volatilestorage unit 110 or displays and outputs processing results of variousprocesses such as an operation result of the operation unit 108.

The operation unit 108 includes an image capturing button and a networksetting button and provides a user interface to the CPU 101 and thecomponents.

The image capturing unit 109 includes an optical lens and acharge-coupled device (CCD) and captures an image such as a still imageor a moving image.

The non-volatile storage unit 110 includes a non-volatile memory andstores the moving image or the still image captured by the imagecapturing unit 109. The non-volatile storage unit 110 can store variousprograms and parameters.

The movement detection unit 111 detects a movement of the UE 1.

Based on a result of detecting the movement thereof by the movementdetection unit 111, the channel selection unit 112 selects a basestation (BS) from among a plurality of base stations (BSs) connected tothe UE 1. A paging signal from a paging channel (hereinafter referred toas a PCH) corresponding to the selected base station is to be monitored.The PCH is a control channel via which data can be transmitted from theBS to all pieces of UE in a cell. The paging signal (hereinafterreferred to as a PCH signal) is a notification signal for controllingthat is transmitted from the base station to all of the pieces of UE viathe PCH.

The power supply source determination unit 113 determines the type of apower supply that is feeding power to the UE 1 or an apparatus includingthe UE 1.

The power unit 114 supplies power to the components of the UE 1 or theapparatus including the UE 1.

<State Transition of Communication Apparatus>

FIG. 2 is a diagram illustrating a state transition of the UE 1compliant with the 5G public wireless communication standard defined inthe 3GPP standard.

The UE 1 transitions between three states. RRC_CONNECTED is the state(mode) where a unicast wireless communication path to a BS is connected,a wireless communication resource for data communication is allocated,and the UE 1 can perform unicast data communication.

If receiving a release signal 21 of radio resource control (RRC) fromthe base station (BS), the UE 1 transitions to RRC_IDLE.

RRC_IDLE is a state (mode) where the unicast wireless communication pathto the BS is not connected, the wireless communication resource for datacommunication is released, and the UE 1 cannot perform the unicast datacommunication. In RRC_IDLE, the UE 1 can only receive a control signalbroadcast from the BS.

If receiving a connection signal 22 of RRC from the BS, the UE 1 returnsto RRC_CONNECTED.

If receiving an inactivation signal 23 of RRC from the BS in theRRC_CONNECTED state, the UE 1 transitions to RRC_INACTIVE.

RRC_INACTIVE is a mode where the unicast wireless communication path tothe BS is not connected, but the wireless communication resource fordata communication remains to be allocated. In RRC_INACTIVE, the UE 1cannot perform the unicast data communication, but can only receive acontrol signal broadcast from the BS.

If receiving a connection signal 24 of RRC from the BS, the UE 1 returnsto RRC_CONNECTED.

FIGS. 3A, 3B, and 3C are diagrams schematically illustrating a use stateof wireless communication path where the UE 1, which is executing DC,uses the wireless communication path to a plurality of BSs via a publicwireless communication network. FIG. 3A illustrates the use state of thewireless communication path in RRC_CONNECTED. FIGS. 3B and 3C illustratethe use state of the wireless communication path in RRC_INACTIVE.

In RRC_CONNECTED in FIG. 3A, if receiving the inactivation signal 23from a base station (MCG_BS) 31 that controls a group of master cells,the UE 1 transitions to RRC_INACTIVE. A master cell (primary cell) is acell that guarantees connection between the UE 1 and a wireless network.Hereinafter, a base station (MCG_BS) that controls a group of mastercells is referred to as a master cell base station.

In RRC_INACTIVE in FIGS. 3B and 3C, if receiving the connection signal24 from the master cell base station (MCG_BS) 31, the UE 1 returns toRRC_CONNECTED.

With reference to FIG. 3A, in RRC_CONNECTED, the UE 1 monitors a PCH 31a via which the master cell base station (MCG_BS) 31 transmits a PCHsignal. Simultaneously, the UE 1 monitors a PCH 32 a via which a basestation (SCG_BS) 32 that controls a group of secondary cells transmits aPCH signal. A secondary cell is a cell that provides a wirelesscommunication resource in addition to the master cell. Hereinafter, abase station (SCG_BS) that controls a group of secondary cells isreferred to as a secondary cell base station.

The UE 1 holds a user channel (UCH) 31 b via which data is transmittedto and received from the master cell base station (MCG_BS) 31, and a UCH32 b via which data is transmitted to and received from the secondarycell base station (SCG_BS) 32.

In the 5G public wireless communication standard, in RRC_INACTIVE, theUE1 continues monitoring of the PCHs while releasing wireless connectionof UCHs. Since the UE1 holds the wireless communication resource for thebase station, a procedure for reconnecting to the same base station issimplified.

However, the 5G public wireless communication standard does not definebehavior regarding which PCH to monitor if the UE 1 executing DCtransitions from RRC_CONNECTED to RRC_INACTIVE.

Thus, two methods illustrated in FIGS. 3B and 3C are possible.

FIG. 3B illustrates a case where the UE 1 continues monitoring of a PCHsignal from both the PCH 31 a for the master cell base station (MCG_BS)31 and the PCH 32 a for the secondary cell base station (SCG_BS) 32.

FIG. 3C illustrates a case where the UE 1 continues the monitoring of aPCH signal from the PCH 31 a for the master cell base station (MCG_BS)31, while the UE 1 discontinues the monitoring of a PCH signal from thePCH 32 a for the secondary cell base station (SCG_BS) 32.

In the method in FIG. 3B, even during RRC_INACTIVE, the UE 1 continuesmonitoring of the PCHs for both the master cell base station (MCG_BS) 31and the secondary cell base station (SCG_BS) 32. Thus, when the UE 1returns to RRC_CONNECTED, the UE 1 can determine in advance whether aunicast wireless communication path for DC can be set. This improvesresponsiveness in resuming a service by the UE 1 on standby, but doesnot minimize power consumption of the UE 1.

On the other hand, in the method in FIG. 3C, the UE 1 transitions to themonitoring of the PCH 31 a for the master cell base station (MCG_BS) 31only. Thus, the power consumption of the UE 1 can be as minimized asthat in the RRC_IDLE state. However, the UE 1 cannot determine whetherthe unicast wireless communication path for DC can be set unless the UE1 returns to RRC_CONNECTED. This reduces the responsiveness in resumingthe service by the UE 1 on standby.

As described above, whether to prioritize the power consumption or animprovement in the responsiveness in resuming the service differsdepending on the characteristics of the service using DC and the stateof the UE 1. Thus, in RRC_INACTIVE, it is difficult to uniquelydetermine which of the methods in FIGS. 3B and 3C is to be used.

In the present exemplary embodiment, depending on the state of the UE 1and the characteristics of the service, a PCH signal from which PCH isto be monitored is selected. Details of such channel selectionprocessing in the present exemplary embodiment will be described belowwith reference to FIGS. 5 to 11.

FIG. 4 illustrates an example of a use case of the UE 1 according to thepresent exemplary embodiment and illustrates an example of a networksystem where the UE 1 as a capture device, i.e., an in-vehicle camera,captures an image while a vehicle is moving or stopped, and the UE 1uploads the captured image to a server.

A vehicle 2 in FIG. 4 includes the UE 1 mounted thereon as an in-vehiclecamera. The vehicle 2 travels from a position within a master cell area1 indicated by a dashed line in FIG. 4 to a position within a mastercell area 2 indicated by a dashed-dotted line. In the master cell area1, a master cell base station (MCG_BS_1) 311 controls master cells. Inthe master cell area 2, a master cell base station (MCG_BS_2) 312controls master cells. Secondary cell base stations (SCG_BS_1 toSCG_BS_3) 321 to 323 each control secondary cells.

Using DC that enables securement of broadband communication, the UE 1secures a unicast wireless communication path to each of the master cellbase stations (MCG_BS_1 and 2) 311 and 312 and the secondary cell basestations (SCG_BS_1 to 3) 321 to 323. Via a core network 4 thataccommodates the master cell base stations (MCG_BS_1 and 2) 311 and 312and the secondary cell base stations (SCG_BS_1 to 3) 321 to 323, the UE1 uploads a captured image to a database 5 in the server. In thedatabase 5, the uploaded captured image can be configured as, forexample, a dynamic map obtained by adding various additional informationnecessary to support self-driving of a vehicle to three-dimensionalgeospatial information. Details of the configuration of the dynamic mapwill be described below with reference to FIG. 12.

During a period when the captured image is to be uploaded, the UE 1mounted on the vehicle 2 is in RRC_CONNECTED. During a period when thecaptured image is not to be uploaded, the UE 1 makes a state transitionto RRC_INACTIVE.

Caused by the movement of the vehicle 2, the UE 1 controls a handoverbetween the master cell base stations (MCG_BS_1 and 2) 311 and 312 and ahandover between the secondary cell base stations (SCG_BS_1 to 3) 321 to323.

A description is given below of control to select a PCH to be monitoredby the UE 1 according to the present exemplary embodiment. An example ofa case is used where cells are switched while the UE 1 as the capturedevice is waiting for the upload service of the captured image to start.

<PCH Automatic Selection Process Based on Monitoring of Moving Speed ofUE 1>

FIG. 5 is a flowchart illustrating an example of a processing procedureof a monitoring control process executed when the UE 1 according to thefirst exemplary embodiment monitors the moving speed of the UE 1.

The UE 1 monitors a movement state of the UE 1 as an internallycontrolled state of the UE 1 in a constant cycle. At each monitoringtiming of the moving speed, the UE 1 starts the processing in FIG. 5.

In step S51, the 5G communication unit 104 of the UE 1 determineswhether the UE 1 is currently connected based on DC and is inRRC_INACTIVE.

If the UE 1 is not currently connected based on DC or is not inRRC_INACTIVE (NO in step S51), the monitoring procedure of PCH signalsto the UE 1 via the PCHs is uniquely determined based on the 5G publicwireless communication standard. Thus, the processing ends.

If the UE 1 is currently connected based on DC and is in RRC_INACTIVE(YES in step S51), then in step S52, the movement detection unit 111 ofthe UE 1 detects the movement state of the UE 1 and supplies the resultof the detection of the movement to the CPU 101, and the processingproceeds to step S53.

In step S53, based on the result of the detection of the movement fromthe movement detection unit 111, the CPU 101 of the UE 1 determineswhether the UE 1 is moving. If the UE 1 is not moving (NO in step S53),the processing proceeds to step S55.

In step S55, the channel selection unit 112 of the UE 1 stops monitoringof a PCH signal transmitted from the secondary cell base station(SCG_BS_1) 321 for a group of secondary cells (SCG) of the UE 1 to theUE 1 via the PCH 32 a, and the processing ends.

If the UE 1 is moving in step S53 (YES in step S53), the processingproceeds to step S54.

In step S54, the channel selection unit 112 of the UE 1 startsmonitoring of the PCH signal transmitted from the secondary cell basestation (SCG_BS_1) 321 to the UE 1 via the PCH 32 a, and the processingproceeds to step S56.

In step S56, the CPU 101 of the UE 1 determines whether, a status whereDC cannot be executed (hereinafter referred to as a DC inexecutablestatus) is defined and is continued for a certain period. The DCinexecutable status referenced in step S56 is set by executingprocessing described below with reference to FIG. 6.

If it is determined that it is within the certain period aftertransition to the DC inexecutable status (NO in step S56), theprocessing proceeds to step S58. In step S58, the CPU 101 of the UE 1continues the RRC_INACTIVE state and ends the processing of a series ofprocesses executed at the monitoring timing of the movement.

If it is determined that the DC inexecutable status continues exceedingthe certain period (YES in step S56), the processing proceeds to stepS57. In step S57, the 5G communication unit 104 of the UE 1 transitionsto RRC_CONNECTED, and the processing ends.

After a return to RRC_CONNECTED is completed, the UE 1 sets a wirelesscommunication path for DC again based on control defined in the 5Gpublic wireless communication standard.

<DC Inexecutable Status Monitoring Process by UE>

FIG. 6 is a flowchart illustrating an example of a processing procedureof a process for determining whether execution of DC can be maintainedand for setting status information regarding the DC inexecutable status.The processing procedure is executed by the UE 1 every time a monitoringtiming of the PCHs comes.

By monitoring the PCHs in a constant cycle, the UE 1 determines whetherthe execution of DC can be maintained. At each monitoring timing of thePCHs, the UE 1 starts the processing in FIG. 6. When the processing inFIG. 6 is executed, the UE 1 is in the RRC_INACTIVE state.

In step S61, the 5G communication unit 104 of the UE 1 determineswhether the UE 1 is executing DC.

If the UE 1 is not executing DC (NO in step S61), the monitoringprocedure of PCH signals to the UE 1 via the PCHs is uniquely determinedbased on the 5G public wireless communication standard. Thus, theprocessing ends.

If the UE 1 is executing DC (YES in step S61), then in step S62, the 5Gcommunication unit 104 of the UE 1 determines whether monitoring of thePCH signal transmitted from the secondary cell base station (SCG_BS_1)321 to the UE 1 via the PCH 32 a is stopped.

If the monitoring of the PCH 32 a for the secondary cell base station(SCG_BS_1) 321 is not stopped (NO in step S62), the processing proceedsto step S63.

In step S63, the 5G communication unit 104 of the UE 1 determineswhether reception of the PCH signal most recently transmitted from thesecondary cell base station (SCG_BS_1) 321 to the UE 1 via the PCH 32 ais successful.

If the reception of the PCH signal most recently transmitted from thesecondary cell base station (SCG_BS_1) 321 to the UE 1 via the PCH 32 ais successful (YES in step S63), the processing proceeds to step S67. Ifthe reception of the PCH signal is not successful (NO in step S63), theprocessing proceeds to step S64.

In step S67, the CPU 101 of the UE 1 clears the DC inexecutable statusheld in the non-volatile storage unit 110, and the processing ends.

If the monitoring of the PCH 32 a for the secondary cell base station(SCG_BS_1) 321 is stopped in step S62 (YES in step S62), then in stepS64, the UE 1 checks content of a PCH signal transmitted from the mastercell base station (MCG_BS_1) 311 via the PCH 31 a.

More specifically, the CPU 101 of the UE 1 checks content of a radioaccess network (RAN)-based notification area, which is notificationinformation that is broadcast using the PCH signal transmitted from themaster cell base station (MCG_BS_) 311.

In step S65, the CPU 101 of the UE 1 determines whether the content ofthe RAN-based notification area checked in step S64 includes informationregarding a cell other than a master cell.

If the information regarding a cell other than a master cell, such as asecondary cell, is not included in the RAN-based notification area (NOin step S65), the processing proceeds to step S66. In step S66, the CPU101 of the UE 1 sets the DC inexecutable status to on, and theprocessing ends.

If information regarding the cell other than the master cell, such as asecondary cell, is included in the RAN-based notification area (YES instep S65), the processing proceeds to step S67. In step S67, the CPU 101of the UE 1 clears the DC inexecutable status, and the processing ends.

As described above, in the present exemplary embodiment, while the UE 1is in the RRC_INACTIVE state, the UE 1 updates the DC inexecutablestatus prior to a wireless reconnection. Then, with continuance of theDC inexecutable status for a certain period as a trigger, the UE 1transitions to RRC_CONNECTED.

<DC Connection Determination Processing Executed when UE 1 Transitionsto RRC_CONNECTED>

FIG. 7 is a flowchart illustrating an example of a processing procedureof DC connection determination processing executed when the UE 1transitions to RRC_CONNECTED.

Every time the UE 1 transitions to RRC_CONNECTED, the UE 1 starts theprocessing illustrated in FIG. 7. In step S71, the 5G communication unit104 of the UE 1 determines whether the UE 1 is executing DC. If the UE 1is not executing DC (NO in step S71), the processing proceeds to stepS77. In step S77, the UE 1 immediately transitions to RRC_CONNECTED, andthe processing ends.

If the UE 1 is executing DC (YES in step S71), the processing proceedsto step S72. In step S72, the 5G communication unit 104 of the UE 1determines whether monitoring of the PCH signal transmitted from thesecondary cell base station (SCG_BS_1) 321 to the UE 1 via the PCH 32 ais stopped.

If the monitoring of the PCH signal from the PCH 32 a for the secondarycell base station (SCG_BS_1) 321 is not stopped (NO in step S72), theprocessing proceeds to step S77. In step S77, the UE 1 immediatelytransitions to RRC_CONNECTED. If the monitoring of the PCH signal fromthe PCH 32 a is stopped (YES in step S72), the processing proceeds tostep S73.

In step S73, the 5G communication unit 104 of the UE 1 resumes themonitoring of the PCH signal transmitted from the secondary cell basestation (SCG_BS_1) 321 to the UE 1 via the PCH 32 a.

In step S74, the 5G communication unit 104 of the UE 1 determineswhether the reception of the PCH signal from the secondary cell basestation (SCG_BS_1) 321 via the PCH 32 a is successful.

If the reception of the PCH signal from the secondary cell base station(SCG_BS_1) 321 via the PCH 32 a is successful (YES in step S74), theprocessing proceeds to step S77. In step S77, the UE 1 immediatelytransitions to RRC_CONNECTED. If the reception of the PCH signal fromthe PCH 32 a is not successful (NO in step S74), the processing proceedsto step S75.

In step S75, the 5G communication unit 104 of the UE 1 makes a request,via the master cell base station (MCG_BS_1) 311 for master cells, tosecure a wireless communication path via a new secondary cell basestation for secondary cells.

If securement of the wireless communication path via the new secondarycell base station requested in step S75 is not successful in step S76(NO in step S76), the 5G communication unit 104 of the UE 1 discontinuesthe execution of DC, and the processing proceeds to step S77. In stepS77, the UE 1 transitions to the RRC_CONNECTED state with only themaster cell base station (MCG_BS_1) 311.

If the securement of the wireless communication path via the newsecondary cell base station is successful (YES in step S76), theprocessing returns to step S74. In step S74, the UE 1 waits to receive aPCH signal from the new secondary cell base station secured in step S76.

<State Transition Sequence of Monitoring Control Processing withMovement of UE>

A state transition sequence of the monitoring control processingexecuted by the UE 1 according to the present exemplary embodiment isdescribed below in chronological order with reference to FIGS. 8 to 11.

The UE 1 as the capture device is mounted on the vehicle 2 asillustrated in FIG. 4 and determines the movement state of the UE 1using information from a sensor installed in the UE 1 or near the UE 1in the vehicle 2. Then, while in RRC_INACTIVE, the UE 1 automaticallyselects a PCH to be monitored by the UE 1 based on the determinedmovement state of the UE 1.

With reference to FIG. 4, the vehicle 2 on which the UE 1 as the capturedevice is mounted is located in the master cell area 1, which iscontrolled by the master cell base station 311. At first, the UE 1executes DC with the master cell base station (MCG_BS_1) 311 and thesecondary cell base station (SCG_BS_1) 321 to use a wirelesscommunication service. For example, the UE 1 uploads a captured image tothe database 5 in the server for a dynamic map.

With reference to FIG. 8, for example, upload of the captured image tothe database 5 in the server by the UE 1 is suspended. In this case, instep S81, the core network 4 and the master cell base station (MCG_BS_1)311 and the secondary cell base station (SCG_BS_1) 321 on RAN detectsuspension of payload data communication with the UE 1. Based on thedetection of the suspension of the payload data communication, the corenetwork 4 and the base stations (the master cell base station 311 andthe secondary cell base station 321) recognize a condition for urgingthe UE 1 to transition from RRC_CONNECTED to RRC_INACTIVE.

In step S82, with recognition of the condition for urging the UE 1 totransition to RRC_INACTIVE as a trigger, the master cell base station(MCG_BS_1) 311 transmits, to the UE 1, a message indicating aninstruction to release an RRC connection.

In step S83, the master cell base station (MCG_BS_1) 311 transmits, tothe secondary cell base station (SCG_BS_1) 321, a message indicating aninstruction to suspend communication to maintain a communication pathsecured for the UE 1.

Then, in step S84, the master cell base station (MCG_BS_1) 311transitions to RRC_INACTIVE. With reception of the messages in steps S82and S83 as a trigger, the UE 1 and the secondary cell base station(SCG_BS_1) 321 also transition to RRC_INACTIVE.

The UE 1, which has transitioned to RRC_INACTIVE, periodically executesthe PCH checking process described above with reference to FIG. 6.

More specifically, the UE 1 executes the PCH checking process at atiming when the master cell base station (MCG_BS_1) 311 transmits thePCH signal to the UE 1 via the PCH 31 a in step S85 and at a timing whenthe secondary cell base station (SCG_BS_1) 321 transmits the PCH signalto the UE 1 via the PCH 32 a in step S86.

At this time, the vehicle 2 on which the UE 1 is mounted moves. At thisstage, in step S87, the PCH signal from the master cell base station(MCG_BS_1) 311 is received by the UE 1, but in step S88, the receptionof the PCH signal from the secondary cell base station (SCG_BS_1) 321 isfailed. In this case, with a failure of the reception of the PCH signaltransmitted to the UE 1 as a trigger, in step S89, the UE 1 detects lossof the PCH signal notified by the secondary cell base station (SCG_BS_1)321 via the PCH 32 a.

Detecting the loss of the PCH signal from the secondary cell basestation (SCG_BS_1) 321 via the PCH 32 a, in step S64 in FIG. 6, the UE 1checks information regarding the RAN-based notification area notified bythe master cell base station (MCG_BS_1) 311 using the PCH signal.

A description is given of an example in a case where informationregarding an effective secondary cell is not included in the RAN-basednotification area. In step S65 in FIG. 6, it is determined that theeffective secondary cell other than a master cell is not included (NO instep S65). Then, in step S66, the UE 1 sets the DC inexecutable statuswhen a wireless reconnection is made.

In a case where the vehicle 2 on which the UE 1 is mounted moves, the DCinexecutable status is set due to a continuous movement in a particulardirection. Thus, even if the UE 1 continues waiting for the PCH signalto be notified by the secondary cell base station (SCG_BS_1) 321, thereception of the PCH signal to be notified by the secondary cell basestation (SCG_BS_1) 321 is not restored.

As described with reference to FIG. 5, with continuance of the DCinexecutable status for a certain period or more as a trigger, the UE 1transitions to RRC_CONNECTED with the master cell base station(MCG_BS_1) 311. Then, when the UE 1 transitions to RRC_CONNECTED withthe master cell base station (MCG_BS_1) 311, in step S75, the UE 1requests, via the master cell base station (MCG_BS_1) 311, the corenetwork 4 to assign a new secondary cell base station.

With reference to FIG. 9, a description is given of an example of thecontrol sequence for the UE 1 associated with the request to assign thenew secondary cell base station.

In step S91, the UE 1 detects that the loss of the signal has continuedfor a certain period after the PCH signal notified by the secondary cellbase station (SCG_BS_1) 321 via the PCH 32 a is lost. With the loss ofthe PCH signal notified by the secondary cell base station (SCG_BS_1)321 as a trigger, as illustrated in FIG. 7, the UE 1 transitions toRRC_CONNECTED with the master cell base station (MCG_BS_1) 311.

Referring back to FIG. 9, in step S92, the UE 1 transmits a resumerequest to resume the RRC connection to the master cell base station(MCG_BS_1) 311.

Receiving the resume request to resume the RRC connection, in step S93,the master cell base station (MCG_BS_1) 311 returns a reconnectionmessage (resume) regarding the RRC connection to the UE 1 and instructsthe UE 1 to reconnect to the master cell base station (MCG_BS_1) 311.

Receiving the reconnection message (resume) regarding the RRCconnection, in step S94, the UE 1 restores a wireless connection withthe master cell base station (MCG_BS_1) 311. Then, the UE 1 returns areconnection completion message (resume complete) regarding the RRCconnection to the master cell base station (MCG_BS_1) 311 and notifiesthe master cell base station (MCG_BS_1) 311 of the completion of thereconnection.

If the master cell base station (MCG_BS_1) 311 receives the reconnectioncompletion message regarding the RRC connection from the UE 1, in stepS95, the master cell base station (MCG_BS_1) 311 transmits areconnection message (resume) to the secondary cell base station(SCG_BS_1) 321.

In step S96, a wireless connection between the secondary cell basestation (SCG_BS_1) 321 and the UE 1 is failed due to deterioration ofquality of a wireless line caused by the movement of the vehicle 2.Thus, in step S97, the secondary cell base station (SCG_BS_1) 321notifies the master cell base station (MCG_BS_1) 311 of the failure ofthe wireless connection using a reconnection response message (resumeresponse).

In step S98, with continuance of the DC inexecutable status for acertain period as a trigger, the UE 1 secures a unicast wirelesscommunication path to the master cell base station (MCG_BS_1) 311,executes the processing in FIG. 7, and transitions to RRC_CONNECTED.

In step S99, the master cell base station (MCG_BS_1) 311 secures acommunication path for a new secondary cell base station and changes thecommunication path for the secondary cell base station. Morespecifically, the master cell base station (MCG_BS_1) 311 changes thecommunication path for the secondary cell base station to acommunication path for a new secondary cell base station (SCG_BS_2) 322.This is a process executed due to a change of the closest secondary cellbase station to the UE 1 from the secondary cell base station (SCG_BS_1)321 to the secondary cell base station (SCG_BS_2) 322 caused by themovement of the vehicle 2.

In step S100, the master cell base station (MCG_BS_1) 311 transmits, tothe old secondary cell base station (SCG_BS_1) 321, a UE Context Releasemessage indicating an instruction to release communication contextsecured for the UE 1.

In step S101, the master cell base station (MCG_BS_1) 311 transmits, tothe UE 1, a release message (release) regarding the RRC connection. Byexecution of steps S100 and S101, the UE 1 recognizes that assignment ofthe communication context is changed from the old secondary cell basestation (SCG_BS_1) 321 to the new secondary cell base station (SCG_BS_2)322 (steps S76 and S74 in FIG. 7).

If the reception of a PCH signal from the new secondary cell basestation (SCG_BS_2) 322 via the PCH 32 a is successful in step S74 inFIG. 7 (YES in step S74), the processing proceeds to step S77. In stepS77, the UE 1 temporarily transitions to RRC_CONNECTED in which DC isused with the master cell base station (MCG_BS_) 311 and the newsecondary cell base station (SCG_BS_2) 322.

Resumption of the payload data communication is not detected yet at thistime after the upload of the captured image to the database 5 of theserver is suspended by the UE 1. In this case, in step S102, the mastercell base station (MCG_BS_1) 311, the secondary cell base station(SCG_BS_2) 322, and the core network 4 recognize this state as acondition for urging the UE 1 to transition from RRC_CONNECTED toRRC_INACTIVE.

With reference to FIG. 10, the UE 1, which has transitioned toRRC_INACTIVE in step S102, periodically executes the PCH checkingprocess described above with reference to FIG. 6.

More specifically, the UE 1 executes the PCH checking process at atiming when the master cell base station (MCG_BS_1) 311 transmits thePCH signal to the UE 1 in step S103 and at a timing when the secondarycell base station (SCG_BS_2) 322 transmits the PCH signal to the UE 1 instep S104.

At this time, the vehicle 2 on which the UE 1 is mounted further moves.At this stage, in step S105, the reception of the PCH signal from themaster cell base station (MCG_BS_1) 311 via the PCH 31 a is failed. Instep S106, the PCH signal from the secondary cell base station(SCG_BS_2) 322 via the PCH 32 a is received by the UE 1 at this stage.In this case, with the failure of the reception of the PCH signaltransmitted to the UE 1 as a trigger, in step S107, the UE 1 detectsdeterioration of quality of the PCH signal from the master cell basestation (MCG_BS_1) 311 via the PCH 31 a caused by the further movementof the vehicle 2.

In a case where the vehicle 2 on which the UE 1 is mounted moves, thequality of the PCH signal from the master cell base station (MCG_BS_1)311 deteriorates due to a continuous movement in a particular direction.Thus, even if the UE 1 continues waiting for the PCH signal from themaster cell base station (MCG_BS_1) 311 via the PCH 31 a, the receptionof the PCH signal from the master cell base station (MCG_BS_1) 311 isnot restored.

In steps S108 to S13, with the deterioration of the quality of the PCHsignal transmitted from the master cell base station (MCG_BS_1) 311 viathe PCH 31 a as a trigger, the UE 1 transitions to RRC_CONNECTED withthe master cell base station (MCG_BS_1) 311. Then, the UE 1 waits forthe assignment of a new master cell base station executed on the corenetwork 4 side.

With reference to FIG. 11, in step S114, on the core network 4 side, itis determined that a handover process from the old master cell basestation (MCG_BS_1) 311 to the new master cell base station (MCG_BS_2)312 is required. Then, the handover process is executed.

Resumption of the payload data communication is not detected yet at thistime after the upload of the captured image to the database 5 of theserver is suspended by the UE 1. Thus, the master cell base station(MCG_BS_2) 312 as a handover destination and the core network 4recognize this state as a condition for urging the UE 1 to transitionfrom RRC_CONNECTED to RRC_INACTIVE.

In step S115, with recognition of the condition for transition toRRC_INACTIVE as a trigger, the master cell base station (MCG_BS_2) 312transmits a message indicating an instruction to release the RRCconnection to the UE 1.

In step S116, the master cell base station (MCG_BS_2) 312 transmits, tothe secondary cell base station (SCG_BS_2) 322, a message indicating aninstruction to suspend the communication with the UE 1.

Then, in step S117, the master cell base station (MCG_BS_2) 312transitions to RRC_INACTIVE. With the reception of the messages in stepsS115 and S116 as a trigger, the UE 1 and the secondary cell base station(SCG_BS_2) 322 also transition to RRC_INACTIVE.

The UE 1, which has transitioned to RRC_INACTIVE, periodically executesthe PCH checking process described above with reference to FIG. 6.

After the vehicle 2 on which the UE 1 is mounted stops moving, thequality of a PCH signal transmitted from the master cell base station(MCG_BS_2) 312 to the UE 1 via the PCH 31 a in step S118 and the PCHsignal transmitted from the secondary cell base station (SCG_BS_2) 322to the UE 1 via the PCH 32 a in step S119 do not change.

With reference to FIG. 5, after the UE 1 recognizes stoppage of thevehicle 2 (NO in step S53), in step S55, the UE 1 stops monitoring ofthe PCH signal notified by the secondary cell base station (SCG_BS_2)322 via the PCH 32 a until the movement of the vehicle 2 is started.

FIG. 12 illustrates examples of types of information uploaded to thedatabase 5 in the map server, as a dynamic map creation server, by theUE 1, as the capture device mounted on the vehicle 2, and types ofcommunication services corresponding to the types of information. Theplurality of communication services illustrated in FIG. 12 is in astandby state while the UE 1 as the capture device is in RRC_INACTIVE,and is scheduled to be executed after the UE 1 returns to RRC_CONNECTED.

A dynamic map 122 illustrated in FIG. 12 is divided into pieces ofinformation that are updated at different frequencies.

More specifically, the dynamic map 122 includes dynamic information thatis updated about every second, quasi-dynamic information that is updatedabout every minute, quasi-static information that is updated about everyhour, and static information that is updated about every month.

Among a plurality of types of communication services 121, for example, amoving image captured during low-speed travelling on a general road inwhich a changing state of pedestrians and traffic signals on the streetcan be grasped is uploaded as dynamic information about every second.For example, the moving image or the still image captured duringtravelling in which, with detection of an image of a traffic jam or anaccident as a trigger, occurrence of the detected traffic jam oraccident can be grasped is uploaded as quasi-dynamic information aboutevery minute.

For example, a still image captured during travelling in which, withdetection of an image of construction or regulation as a trigger,occurrence of the detected construction or regulation can be grasped isuploaded as quasi-static information about every hour. For example, amoving image or a still image captured during travelling in which, withdetection of an image of a building or a lane that is not included inmap information in use as a trigger, the detected building or anincrease in lanes can be grasped is uploaded as static information aboutevery month.

In the above-described use case of the dynamic map creation server, inthe present exemplary embodiment, during the period when the capturedimage is to be uploaded, the UE 1 transitions to RRC_CONNECTED. Duringthe period when the captured image is not to be uploaded, the UE 1transitions to RRC_INACTIVE. Then, while the vehicle 2 on which the UE 1as the capture device is mounted is travelling, in the RRC_INACTIVEstate, the UE 1 monitors PCHs for both a master cell base station and asecondary cell base station and receives PCH signals from both themaster cell base station and the secondary cell base station.

To detect the movement of the UE 1 as the capture device mounted on thevehicle 2 according to the present exemplary embodiment, for example,the movement detection unit 111 of the UE 1 may detect the movement byusing an acceleration sensor. Alternatively, the movement may bedetected by the GPS reception unit 106 of the UE 1 by updating a GPSsignal transmitted from the GPS.

Yet alternatively, the movement may be detected by the power supplysource determination unit 113 of the UE 1 by monitoring a state of eachpower feed line of the vehicle 2 on which the UE 1 is mounted anddetecting a change in a power feed line to the vehicle 2. For example,while power is fed from an ignition (IG) power supply, it may bedetected that the vehicle 2 is moving. While power is fed from anaccessory (ACC) power supply, it may be detected that the vehicle 2 isstopped.

Yet alternatively, the power supply source determination unit 113 of theUE 1 may detect the movement based on a change in a value of a receivedsignal strength indicator (RSSI) of a PCH signal intermittently notifiedby a base station.

As described above, according to the present exemplary embodiment, thestate of the communication apparatus 1 transitions between RRC_CONNECTEDand RRC_INACTIVE in the state where unicast communication paths via amaster cell base station and via a secondary cell base station aresecured using DC. For example, during the period when a captured imageis to be uploaded, the communication apparatus 1 transitions toRRC_CONNECTED. During the period when the captured image is not to beuploaded, the communication apparatus 1 transitions to RRC_INACTIVE.

Then, the communication apparatus 1 detects the movement state of thecommunication apparatus 1. The communication apparatus 1 switchesmonitoring target channels so that, while the communication apparatus 1is detecting the movement, the communication apparatus 1 monitors PCHsignals transmitted from both the master cell base station and thesecondary cell base station via PCHs for the respective base stationsand, while the communication apparatus 1 is not detecting the movement,the communication apparatus 1 monitors only the PCH signal transmittedfrom the master cell base station via the PCH for the master cell basestation.

Consequently, in a communication apparatus using DC that enablesbroadband communication, it is possible to achieve a reduction in powerconsumption while avoiding a reduction in service responsiveness causedby the movement of the apparatus.

With reference to FIGS. 13 and 14, differences between a secondexemplary embodiment and the first exemplary embodiment are described indetail below. In the first exemplary embodiment, a PCH to be monitoredis selected, during RRC_INACTIVE, based on the movement state of thecommunication apparatus 1. In contrast, in the second exemplaryembodiment, a PCH to be monitored is selected, during RRC_INACTIVE,based on response characteristics required by a service on standby thatis to be executed when the communication apparatus 1 returns toRRC_CONNECTED as the internal control state of the communicationapparatus 1.

FIG. 13 is a diagram illustrating an example of the hardware andfunction configuration of a UE 1 according to the second exemplaryembodiment. As illustrated in FIG. 13, the UE 1 according to the presentexemplary embodiment includes a service information storage unit 115 inaddition to components like those in the first exemplary embodimentillustrated in FIG. 1. In the UE 1 illustrated in FIG. 13, the movementdetection unit 111 may be omitted.

With respect to each service provided in the UE 1, the serviceinformation storage unit 115 stores responsiveness required after the UE1 returns to RRC_CONNECTED, such as a high responsiveness or a lowresponsiveness, as service information. The service information can bedefined based on a real time quality required by a service to beresumed, an amount of data to be transmitted, and a movement state ofthe UE 1.

For example, in the use case where the UE 1 as the capture device ismounted on the vehicle 2, a service that streams a moving image ofpedestrians in the vicinity of an intersection captured while thevehicle 2 is travelling and a steering operation of the vehicle 2 isperformed requires high responsiveness. On the other hand, a servicethat distributes a captured image for crime prevention triggered bydetection of an abnormality by a sensor mounted on the vehicle 2 whilethe vehicle 2 is not travelling does not require high responsiveness. Asdescribed above, in the present exemplary embodiment, the serviceinformation storage unit 115 stores the response characteristics foreach service on standby to be executed by the UE 1.

<PCH Automatic Selection Process Based on Monitoring of ServiceScheduled to be Executed by UE 1>

FIG. 14 is a flowchart illustrating an example of the processingprocedure of a monitoring control processing executed when the UE 1according to the second exemplary embodiment monitors a servicescheduled to be operated after the UE 1 returns to RRC_CONNECTED.

The UE 1 monitors the state of a service scheduled to be executed by theUE 1 on a constant cycle. Every time the monitoring timing of the stateof the service comes, the UE 1 starts the processing in FIG. 14.

A process of step S51 is like that of step S51 illustrated in FIG. 5 inthe first exemplary embodiment.

If the UE 1 is in RRC_INACTIVE in step S51 (YES in step S51), theprocessing proceeds to step S141. In step S141, the service informationstorage unit 115 of the UE 1 determines responsiveness required by theservice on standby scheduled to be executed after the UE 1 returns toRRC_CONNECTED with reference to the stored service information.

If it is determined in step S142 that the service scheduled to beexecuted after the UE 1 returns to RRC_CONNECTED does not need to beresumed with high responsiveness (NO in step S142), the processingproceeds to step S55. In step S55, the UE 1 stops a process of receivinga PCH signal transmitted from the secondary cell base station (SCG_BS_1)321 to the UE 1 via the PCH 32 a.

If it is determined that the service scheduled to be executed after theUE 1 returns to RRC_CONNECTED needs to be resumed with highresponsiveness (YES in step S142), the processing proceeds to step S54.In step S54, the UE 1 starts the process of receiving the PCH signaltransmitted from the secondary cell base station (SCG_BS_1) 321 to theUE 1 via the PCH 32 a of a secondary cell.

Processes of steps S56 to S58 are like processes of steps S56 to S58illustrated in FIG. 5.

After a return to RRC_CONNECTED is completed, the UE 1 sets a wirelesscommunication path for DC again based on control defined in the 5Gpublic wireless standard.

With reference to FIG. 12, for example, the UE 1 can switch monitoringtarget channels so that, while the UE 1 is detecting the wait for theupload of “a moving image captured during low-speed travelling on ageneral road”, which requires high responsiveness, the channel selectionunit 112 of the UE 1 monitors PCH signals transmitted from both a mastercell base station and a secondary cell base station and, while the UE 1is detecting the wait for the upload of “a moving image or a still imagecaptured during travelling” for grasping the occurrence of constructionor regulation on a roadway, which does not require high responsiveness,the channel selection unit 112 of the UE 1 monitors only the PCH signaltransmitted from the master cell base station.

For example, if a service that requires a response within one second isto be resumed, the channel selection unit 112 of the UE 1 may monitorthe PCH signals from both the master cell base station and the secondarycell base station.

As described above, in the present exemplary embodiment, the state ofthe communication apparatus 1 transitions between RRC_CONNECTED andRRC_INACTIVE in the state where unicast communication paths via a mastercell base station and via a secondary cell base station are securedusing DC.

Then, the communication apparatus 1 detects the state of a service onstandby in the communication apparatus 1. The communication apparatus 1switches between monitoring target channels so that, while thecommunication apparatus 1 is detecting that a service that requires highresponsiveness is on standby, the communication apparatus 1 monitors PCHsignals transmitted from both the master cell base station and thesecondary cell base station via PCHs for the respective base stationsand, while the communication apparatus 1 is not detecting that theservice that requires the high responsiveness is on standby, thecommunication apparatus 1 monitors only the PCH signal transmitted fromthe master cell base station via the PCH for the master cell basestation.

Consequently, in a communication apparatus using DC that enablesbroadband communication, it is possible to achieve a reduction in powerconsumption while avoiding a reduction in service responsiveness causedby the movement of the apparatus.

The present disclosure can also be implemented by a program forachieving part or one or more functions of the above-described exemplaryembodiments. More specifically, the present disclosure can beimplemented by processing of supplying the program to a system or anapparatus via a network or a storage medium and causing one or moreprocessors of a computer (or a CPU or a microprocessor unit (MPU)) ofthe system or the apparatus to read and execute the program. The programrecorded in a computer-readable recording medium may be provided.

The present disclosure is not limited to implementation of the functionsaccording to the exemplary embodiments by executing the program read bythe computer. For example, based on an instruction from the program, anoperating system (OS) operating on the computer may perform part or allof actual processing, accordingly implementing the functions accordingto the above-described exemplary embodiments.

As described above, in a communication apparatus that simultaneouslyconnects to a plurality of base stations, it is possible to avoid delayin provision of a service on a network while reducing power consumption.

OTHER EMBODIMENTS

Embodiment(s) of the present disclosure can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present disclosure has been described with reference toexemplary embodiments, it is to be understood that the scope of thepresent disclosure is not limited to the particular disclosed exemplaryembodiments. The scope of the following claims is to be accorded thebroadest interpretation so as to encompass all such modifications andequivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2019-081071, filed Apr. 22, 2019, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A communication apparatus comprising: atransition unit configured to, in a case where a wireless communicationpath to each of a first base station and a second base station isestablished, transition from an RRC_CONNECTED state to an RRC_INACTIVEstate compliant with a 3rd Generation Partnership Project standard; anda control unit configured to, in a case where the transition unittransitions to the RRC_INACTIVE state, perform control to selectivelyexecute operating in a first mode for waiting for a notification signalfrom each of the first and second base stations or operating in a secondmode for waiting for a notification signal from either the first basestation or the second base station, based on a state of thecommunication apparatus.
 2. The communication apparatus according toclaim 1, wherein the first base station is a base station for a mastercell compliant with the 3rd Generation Partnership Project standard, andwherein the second base station is a base station for a secondary cell.3. The communication apparatus according to claim 1, wherein, based on amovement state of the communication apparatus, the control unitselectively executes operating in the first mode or operating in thesecond mode.
 4. The communication apparatus according to claim 1,further comprising a determination unit configured to determine whetherthe communication apparatus is moving, wherein, in a case where thedetermination unit determines that the communication apparatus ismoving, the control unit performs control to operate in the first mode.5. The communication apparatus according to claim 1, wherein, based on apower supply state of the communication apparatus, the control unitselectively executes operating in the first mode or operating in thesecond mode.
 6. The communication apparatus according to claim 1,wherein, based on a service provided by the communication apparatus, thecontrol unit selectively executes operating in the first mode oroperating in the second mode.
 7. The communication apparatus accordingto claim 1, wherein the communication apparatus establishes the wirelesscommunication path to each of the first and second base stations using adual connectivity function compliant with the 3rd Generation PartnershipProject standard.
 8. The communication apparatus according to claim 1,wherein the notification signal is a paging channel signal compliantwith the 3rd Generation Partnership Project standard.
 9. Thecommunication apparatus according to claim 1, wherein the control unitperiodically selects whether to operate in the first mode or operate inthe second mode.
 10. A control method for controlling a communicationapparatus, the control method comprising: transitioning, in a case wherea wireless communication path to each of a first base station and asecond base station is established, from an RRC_CONNECTED state to anRRC_INACTIVE state compliant with the 3rd Generation Partnership Projectstandard; and performing control to, in a case where transition is madeto the RRC_INACTIVE state, selectively execute operating in a first modefor waiting for a notification signal from each of the first and secondbase stations or operating in a second mode for waiting for anotification signal from either the first base station or the secondbase station, based on a state of the communication apparatus.
 11. Anon-transitory computer-readable storage medium storing a computerprogram for causing a computer to execute a method comprising:transitioning, in a case where a wireless communication path to each ofa first base station and a second base station is established, from anRRC_CONNECTED state to an RRC_INACTIVE state compliant with the 3rdGeneration Partnership Project standard; and performing control to, in acase where transition is made to the RRC_INACTIVE state, selectivelyexecute operating in a first mode for waiting for a notification signalfrom each of the first and second base stations or operating in a secondmode for waiting for a notification signal from either the first basestation or the second base station, based on a state of thecommunication apparatus.